Electrical junction joint assemblies such as a “crab joints” are used in low voltage secondary power distribution networks. A crab joint basically includes a central hub (referred to as the “busbar”) with multiple fusible connections (referred to as “limiters”) to a number of cables constituting part of the network. The limiters act to protect the cables connected to them in case of failure of any of the cables in the network.
The conventional crab joint used by some electrical utilities uses compression connectors with EPDM rubber seals to connect network cables to the busbar. The limiter elements cannot be individually replaced. In the conventional-crab joint design, a failed or blown limiter is not readily discernable from the exterior of the crab joint. This makes it very hard for a casual observer to detect an opened limiter in a crab joint. These conditions may go undetected for a long time. When and if customers complain about low voltage in the area or overloading of a network transformer, troubleshooting crews are deployed to look for blown limiters and for open secondary mains in the area. However, each limiter must be tested in a chosen manhole. Troubleshooting blown limiters takes time and it may be crucial to restore customers' service or to mitigate the overload as soon as possible. It has been suggested by others to provide a crab joint that provides a visual indication when a limiter thereof has blown.
Power distribution connections as discussed above are typically housed in an above-ground cabinet or a below-grade box. The connections may be subjected to moisture and may even become submerged in water. If the cable conductors or conductor members of the busbars are left exposed, water and environmental contaminants may cause short circuit failure and/or corrosion thereon. The conductor members of the busbars are sometimes formed of aluminum, so that water may cause oxidation of the conductor members. Such oxidation may be significantly accelerated by the relatively high voltages employed (typically 120 volts to 1000 volts).